The Chandrayaan-1 X-ray Spectrometer: First results

We present X-ray fluorescence observations of the lunar surface, made by the Chandrayaan-1 X-ray Spectrometer during two solar flare events early in the mission (12th December 2008 and 10th January 2009). Modelling of the X-ray spectra with an abundance algorithm allows quantitative estimates of the MgO/SiO₂ and Al₂O₃/SiO₂ ratios to be made for the two regions, which are in mainly basaltic areas of the lunar nearside. One of these ground tracks includes the Apollo 14 landing site on the Fra Mauro Formation. Within the 1σ errors provided, the results are inside the range of basaltic samples from the Apollo and Luna collections. The Apollo 14 soil composition is in agreement with the results from the January flare at the 1σ uncertainty level. Discrepancies are observed between our results and compositions derived for the same areas by the Lunar Prospector gamma-ray spectrometer; some possible reasons for this are discussed.     

Consolidation Parameters Interpretation of CPTU Dissipation Data Based on Strain Path Theory for Soft Jiangsu Quaternary Clays

When a piezocone (CPTU) penetrates the ground, pore pressures are set up due to the stress changes. Pore pressure dissipation occurs in the subsequent consolidation process in a manner dependent on the initial stress distribution. The process of analysis can be used to interpret the consolidation parameters from CPTU data based on strain path approach. For the two approaches to the CPTU analysis, the Houlsby and Teh method used an elastic-plastic model, while the Levadoux and Baligh solution used parameters specifically appropriate for Boston Blue Clay. This article discusses a comparison between the two theoretical predictions and field CPTU measurements deployed in Jiangsu (China) Quaternary clays. The values of the coefficient of consolidation calculated from the two methods are then compared with high-quality laboratory tests. Both theoretical predictions provide good agreement for the shape of the dissipation curve, but the predicted c _h values are different and thought should indeed be given to the use of an appropriate value of G/s _u.     

Scanning sky monitor (SSM) onboard AstroSat

Scanning Sky Monitor (SSM) onboard AstroSat is an Xray sky monitor in the soft X-ray band designed with a large field of view to detect and locate transient X-ray sources and alert the astronomical community about interesting phenomena in the X-ray sky. SSM comprises position sensitive proportional counters with 1D coded mask for imaging. There are three detector units mounted on a platform capable of rotation which helps covering about 50% of the sky in one full rotation. This paper discusses the elaborate details of the instrument and few immediate results from the instrument after launch.     

Comparative study on projected clustering methods for hyperspectral imagery classification

In this study, projected clustering is introduced to hyperspectral imagery for unsupervised classification. The main advantage of projected clustering lies in its ability to simultaneously perform feature selection and clustering. This framework also allows selection of different sets of dimensions (features/bands) for different clusters. This framework provides an effective way to address the issues associated with the high dimensionality of the data. Experiments are conducted on both synthetic and real hyperspectral imagery. For this purpose, projected clustering algorithms are implemented and compared with k-means and k-means preceded by principal component analysis. Preliminary analyses of studied algorithms on synthetic hyperspectral imagery demonstrate good results. For real hyperspectral imagery, only ORCLUS is able to produce acceptable results as compared to other unsupervised methods. The main concern lies with identification of right parameter settings. More experiments are required in this direction.     

Yield estimation of summer crops grown in a mixed cropping area,a spectral growth curve profile approach

Estimation of crop production in advance of the harvest has been an intensively researched field in agriculture. Spectral parameters derived from the spectral growth profile being indicator of growth and development characteristics of the crop have a direct utility in crop-yield modeling. The present study is undertaken in a mixed cropping area of Karveer taluka, Kolhapur district, Maharashtra, to assess feasibility of multi-date moderately coarse WiFS data in developing spectral growth curves following Badhwar model (1980) for summer groundnut and paddy. The analysis highlighted potential of moderately coarse resolution WiFS data in discriminating the crops grown in fragmented conditions, provided detailed and adequate ground truth is used. The regression models using spectral parameters explained 94 % variation in paddy yield. However, model using ground information as peak LAI in addition to spectral variables, could explain 91 % variation in groundnut yield; thus for prediction of low-yielding and poorly managed crop a convergent model is essential. Vegetative growth rate during the pre-heading phase and total growing season absorbed photosynthetically active radiation (APAR) indicated by the area under the curve are the main predictors.     

Mapping Collaboration in Open Source Geospatial Ecosystem

Over the last decade, there has been a tremendous growth and exploitation of open source geospatial software and technologies. A combination of factors is driving this momentum, including the contributions made by hundreds of developers and the leading role played by the Open Source Geospatial Foundation (OSGeo), aiming primarily to support and promote the collaborative development of open source geospatial technologies and data. This article seeks to map out the social history of collaborative activities within the OSGeo ecosystem. We used the archival logs of developers' contributions, specifically looking for boundary spanning activities where contributions crossed multiple projects. The analysis and visualization of these activities allow us to have a better understanding of the role of boundary spanning in the resourcing of each project, the incubation mechanism advocated by OSGeo, and the significance of the social interrelatedness among projects. The data consisted of the subversion (SVN) commit history made by individual developers in the programming code repository. We applied several network analytical and visualization techniques to explore the data. Our findings indicate that more than one in seven developers spanned multiple projects which potentially had the effects of shaping the projects' directions, and increased knowledge flow and innovation. In addition, the OSGeo's incubation mechanism provided an important encouragement for boundary spanning and increased knowledge sharing. By studying the social history of contributions, further tools can be developed in future to assist tracking of the social history, and make developers mindful of the significance of the interdependence among projects and hence continuously contribute to the health of the OSGeo ecosystem.     

The great 1950 Assam Earthquake revisited: Field evidences of liquefaction and search for paleoseismic events

Extensive field investigations were carried out for the first time in the meizoseismal area of the great 1950 Assam Earthquake aimed at exploring the paleoseismic history of the NE Indian region through documentation of liquefaction features and radiocarbon (¹⁴C) dating. Trenching at more than a dozen locations along the Burhi Dihing River valley and within the alluvial fans adjoining the Brahmaputra and Dibang Rivers resulted in the identification of more than a dozen very prominent liquefaction features (sand dykes, sills, sand blows etc.) as evidences of large to great earthquakes. ¹⁴C dating of the organic material associated with some of the features indicates a paleoseismic record of about 500 yrs archived by the sediments in this region. Compelling geological evidence(s) of the great 1950 earthquake are well constrained by ¹⁴C dating. Out of the two historically reported seismic events (1548 AD and 1697 AD) from this region, ¹⁴C dating could constrain the 1548 AD event though not distinctly. Further studies using combined ¹⁴C and OSL dating may better constrain the seismo-chronology of the study region.     

Characterization of mesostasis regions in lunar basalts: Understanding late‐stage melt evolution and its influence on apatite formation

Recent studies geared toward understanding the volatile abundances of the lunar interior have focused on the volatile‐bearing accessory mineral apatite. Translating measurements of volatile abundances in lunar apatite into the volatile inventory of the silicate melts from which they crystallized, and ultimately of the mantle source regions of lunar magmas, however, has proved more difficult than initially thought. In this contribution, we report a detailed characterization of mesostasis regions in four Apollo mare basalts (10044, 12064, 15058, and 70035) in order to ascertain the compositions of the melts from which apatite crystallized. The texture, modal mineralogy, and reconstructed bulk composition of these mesostasis regions vary greatly within and between samples. There is no clear relationship between bulk‐rock basaltic composition and that of bulk‐mesostasis regions, indicating that bulk‐rock composition may have little influence on mesostasis compositions. The development of individual melt pockets, combined with the occurrence of silicate liquid immiscibility, exerts greater control on the composition and texture of mesostasis regions. In general, the reconstructed late‐stage lunar melts have roughly andesitic to dacitic compositions with low alkali contents, displaying much higher SiO₂ abundances than the bulk compositions of their host magmatic rocks. Relevant partition coefficients for apatite‐melt volatile partitioning under lunar conditions should, therefore, be derived from experiments conducted using intermediate compositions instead of compositions representing mare basalts.     

Hydrometeorological assessments and suspended sediment delivery from a central Himalayan glacier in the upper Ganga basin

Integrated hydrometeorological investigations are not frequently available at a regional scale over a longer time period, especially near the terminus of Indian Himalayan glaciers. An integrated approach to the collection of hydrological data has major advantages for understanding the runoff generation mechanisms at basin scale, particularly when coupled with meteorological observations. The current study involves time series analysis of hydrometeorological records collected near the terminus of the Chorabari Glacier, for four consecutive ablation seasons(June-Sept.) 2009-2012. The analysis shows that variation in rainfall was higher(c_v= 0.9) at the same elevation over proximal sites, while the intensity of extreme rainfall events was 121-160 mm/d. The diurnal temperature range(DTR) has a tendency to reduce over the ablation season because of the onset of the Indian Summer Monsoon(ISM) and then further increases during the ISM withdrawal indicating humid-temperate conditions. The peak discharge(Qpeak) was found to be higher during July and August. Snow and glacier melt contributed 76% of the total suspended sediment transport during peak ISM months(July and August) reflecting seasonal evolution of the hydrologic conduits. The results indicate that Karakoram and western Himalayan glaciers produce comparatively low sediment yield compared to central Himalayan glaciers. The hydrological variations are depicted through flow duration curves(FDC) for meltwater discharge and sediment load. The flow corresponding to Q_(50), Q_(75), and Q_(90)(where Qx is the discharge that is exceeded x percent of the time referred to as % dependability) are 4.2, 3.7, and 2.8 m~3/s; and the corresponding dependability for suspended sediment loads(SSLs) are 409.0, 266.0, and 157.2 t/d, respectively. The daily SSL and discharge(Q) from 2009 to 2012 were used to develop a sediment rating curve(SSL = 39.55 × Q~(1.588). R~2 = 0.8).Multiple regressions are used to determine the impacts of meteorological parameters on glacier melt.The meteorological conditions, hydrological characteristics, and suspended sediment delivery for the Chorabari Glacier provide insight on meltwater generation processes and sediment transport patterns during the ISM season.     

Measurements of radon flux and soil-gas radon concentration along the Main Central Thrust, Garhwal Himalaya, using SRM and RAD7 detectors

Radon in the Earth’s crust or soil matrix is free to move only if its atoms find their way into pores or capillaries of the matrix. ²²²Rn atoms from solid mineral grains get into air, filling pores through emanation process. Then ²²²Rn enters into the atmosphere from air-filled pores by exhalation process. The estimation of radon flux from soil surface is an important parameter for determining the source term for radon concentration modeling. In the present investigation, radon fluxes and soil-gas radon concentration have been measured along and around the Main Central Thrust (MCT) in Uttarkashi district of Garhwal Himalaya, India, by using Scintillation Radon Monitor (SRM) and RAD7 devices, respectively. The soil radon gas concentration measured by RAD7 with soil probe at the constant depth was found to vary from 12 ± 3 to 2330 ± 48 Bq·m^?3 with geometrical mean value of 302 ± 84 Bq·m^?3. Th significance of this work is its usefulness from radiation protection point of view.